A secondary battery has a power-generating element which performs charge and discharge and a case which accommodates the power-generating element. The power-generating element is formed of a positive electrode plate, a negative electrode plate, and a separator disposed between the positive electrode plate and the negative electrode plate. The positive electrode plate and the negative electrode plate are wound with the separator interposed between them to form the power-generating element.
On the other hand, the case is provided with a positive electrode terminal and a negative electrode terminal which are used to electrically connect the secondary battery to a load. A positive electrode internal terminal housed in the case is used to electrically connect the positive electrode terminal to the positive electrode plate of the power-generating element. A negative electrode internal terminal housed in the case is used to electrically connect the negative electrode terminal to the negative electrode plate of the power-generating element.
In a so-called square-type secondary battery, the power-generating element is housed in a rectangular case. The power-generating element is formed to have a shape conforming to an inner wall face of the case, and is thus partially bent. The positive electrode plate and the negative electrode plate are folded back in the bent portions of the power-generating element.